1. Field of the Invention
This invention relates to data transfer methodologies and, more particularly, to bus architecture.
2. Description of the Related Art
Typical computer systems use a low pin count (LPC) bus to connect a southbridge to one or more slave devices, e.g., low bandwidth devices. The LPC bus was designed to replace the older Industry Standard Architecture (ISA) bus. However, using the LPC bus may introduce some routing constraints and routing congestion, because space on system motherboards is very limited and the LPC bus typically requires seven to thirteen signal lines. The LPC bus also has restrictions that limit the length of the wires, which could introduce additional routing challenges to system designers.
Increasingly, personal computer (PC) manufacturers are required to include a trusted platform module (TPM) in computer systems to provide secure storage of data and encryption keys. The TPM is an LPC device that responds to a standard set of commands sent from the PC processor via the LPC bus. Currently, TPM devices are packaged and sold in a standard 40-pin QFN package or a 28-pin TSSOP package. Either of these 28-pin and 40-pin packages takes up a significant amount of board space and is therefore very costly to include in computer systems.
Microsoft® has included the TPM as part of their logo program, which makes the TPM a required feature for platforms wishing to include this particular Microsoft® logo. Based on the increased industry and market requirements, PC manufacturers will soon include a TPM in most of their product models; therefore, it is crucial to decrease the cost of supplying TPMs.